Have you ever lost something that you didn't even realize what is it?

Yes I did

I thought I've lost something in each day I've been through. And I didn't realize what it is, maybe because there're too many things. Maybe happiness, joyful, thanks, trust, spirit, or anything else
One thing that I realize is I'm not used to be myself, not like one or two years ago. Now I often feel not comfort in some ways or situations & there're lots of things which made me to be so.
How long can I hold on this thing? :(